The present invention relates generally to new and useful improvements in a rotatable abrading device of the type commonly referred to as centrifugal blasting machines, and more particularly to the throwing wheels and blade assemblies that are used in such machines.
Abrasive blasting machines having a wheel or rotor assembly provided with a plurality of abrasive throwing blades or vanes arranged radially about the face of the rotor are well known. In use, a stream of abrasive particulate material is fed into the path of the rotating wheel from an impeller secured to the rotor. The blades are adapted to receive and throw the abrasive from the periphery of the rotor at an appropriate discharge point in the machine casing at a blasting velocity to strip or clean metal castings or the like.
The throwing vanes due to the nature of their use are subject to excessive wear and are, therefore, removably mounted on a runnerhead portion of the wheel assembly for replacement as needed. There are two basic styles of runnerhead assemblies, a single-sided runnerhead and double-sided runnerhead. The use of a single-sided runnerhead is advantageous to reduce the “overhung load” on the shaft of the motor or spindle. On the other hand, the double-sided runnerhead may protect the internal liners on the front of the wheel housing. Many different methods of fixing the blades to a runnerhead assembly have been employed.
One inherent problem with either the single-sided or the double-sided runnerhead is the possibility of a blade “shot-locking” in the runnerhead. Shot-locking occurs when abrasive and dust wedge in between the blade and the runnerhead. Maintenance is required to hammer the vanes out of the runnerhead. This maintenance results in a loss of valuable operating time. Furthermore, while the blades must be removable, they must also be held securely so that they resist the tremendous centrifugal forces exerted on them when the wheel is operating.
In short, there exists a need in the art for an improved blade and runnerhead locking assembly for securing the blades to the wheel of a centrifugal blasting machine. The improved blades should be easily removed and replaced without the need for special tools or extensive disassembly of the device. The blades should not be susceptible to shot locking or jamming in position due to fine particulate fouling the mounting mechanism.